Stagnation of subducting slabs in the transition zone due to slow diffusion in majoritic garnet

Abstract

Subducting slabs of oceanic lithosphere often stagnate before reaching the lower mantle. Laboratory experiments under high pressures and temperatures show that pyroxene, a common mineral in such slabs, is transformed to its dense, high-pressure counterpart, majorite garnet, at a very slow rate, temporarily keeping the slabs buoyant compared to the surrounding mantle.